The morning of August 12 witnesses the successful completion of an 8,581m tunnel consisting of a 7,000m limestone karst section by the gripper TBM “Yongji” supplied by CREG. Applied to the Lot 4 of Jilin Yinsong Water Supply Project, the machine fulfills its first-phase drive four months ahead of the schedule. 

Lot 4 constructed by the Contractor, CRTG, is the most complicated and difficult construction sections of the overall line among the 3 TBM driven tunnels. Since its launching in June 2015, “Yongji” has overcome numerous geological challenges, such as karst caves, carbonaceous slate sections, fault fracture zones, extra-large water inflows, and a 7km long limestone karst section. In spite of all those unfavorable ground conditions, “Yongji”made a series of construction breakthroughs.

By May 31, 2016, the machine sets a new monthly advance record of 1226m, arousing widespread industrial and academic attention in China. 

The impressive achievement attracted the research team of professionals led by Wang Mengshu, a CAE academician to visit the jobsite from July 16 to July 17. There are many valuable ingredients in the construction experience and fruits of this gripper TBM to be used for future similar projects, the team commented. 

Yinsong Water Supply Project is one of the 170 major projects included in China's 13th National Five-year Plan (2016-2020). The project is historically significant in terms of the scale, length and scope of benefit in Jilin Province. 

The 23km lot 4 Tunnel is scheduled to be completed within 6 years. The CREG designed gripper TBM “Yongji” has sustained an average monthly rate of 613m up over the past 14 months. With the completion of Phase I tunnel, “Yongji” will step over around 1.5km drill&blast tunnel section, and undergo necessary maintenance before continuing to drive Phase II tunnel.